A five year systematic study of body composition in age-stratified cohorts of normal Caucasian, Black, and Asian men and women was completed in June 1991, serving as the foundation to the current proposal. All the standard methods of body composition measurement have been applied: body potassium (TBK), water (TBW), dual photon absorptiometry (DPA), exchangeable sodium (Nae), underwater weighing (UWW), bioimpedance analysis (BIA), electrical capacitance (TOBEC), and anthropometrics. To these measurements have been added the methods available by in-vivo neutron activation analysis (IVNA) at Brookhaven in a 10 percent subset of the same populations. A library of normal values, and a series of translation tables between the values for body fat, lean body mass, bone mass and density, and other derived descriptors of body composition have been produced. Sex, age, fatness, and race are each influential in affecting the results of measurements. We propose to extend the same techniques to Hispanic body composition by studying Puerto Ricans, the major Hispanic population in New York City. These studies will provide a basis for use of these measurements in nutrition, in clinical epidemiology (for example, in hypertension, diabetes, coronary heart disease risk factors, and obesity), and in clinical medicine (in AIDS, osteoporosis, weight reduction, and aging) with ethnic specificity, defining the ranges of normal according to sex, age, race, and fatness, thereby setting the stage for use of these measurements in clinical settings. During the three years of the project, we shall complete the recruitment of the missing cohorts (ages over 85 are underrepresented) for all ethnic groups, using strategies we define. We shall also prepare a summary document for the eight year study of approximately 1700 volunteer studies in a form designed for maximum utility to workers in nutrition, physiology, aging, and the other research communities where body composition parameters are required.